1. Field of the Invention
The present invention relates to a headrest wherein the headrest can be moved forward and backward in relation to a support stay to adjust its position.
2. Description of the Prior Art
Various kinds of headrests which enable their position to be adjusted have been proposed these days, but almost all of them are intended to manually operate them by the knob, lever or the like, while the others which have no means such as the knob are intended to adjust their position by grasping them by a hand and moving them to a desired position.
One of the headrest of the latter type is shown in FIG. 1, which is intended to adjust its position by controlling its inclination and includes a locking device for preventing return action. In this figure, numeral 1 denotes a support means which is mounted on one end of a support stay 2. The other end of the support stay 2 is inserted in a hole provided at the upper portion of a seat back 3 and fixed thereto. The support means 1 is rotatably provided with a headrest frame or movable member 5 through a pivot shaft 4 so as to incline a headrest body 20 about the pivot shaft 4. Movable member 5 is provided with a member 6 which has a plurality of teeth 7 continuously formed along an arc the center of which is the same as that of said pivot shaft 4, land section 8 provided at one end of said teeth 7, and stopper portion 9 disposed at the end of said land section 8. Support member 1 pivotally supports a pawl means 11 through a pin 10 which can be engaged with one of said teeth 7 selectively. Said teeth 7 and paw means 11 construct a device for locking the returning movement of a headrest body 20 in relation to the support stay 2. Further, the support member 1 pivotally supports a hook 13 which can be engaged with a hanger portion 14 provided at the end of the pawl means 11 for holding said pawl means 11 in the condition of being released from the teeth 7. The pawl means 11 is operatively connected with the hook 13 through a coil spring 15 which acts for rotating both of said means 11 and 13 in anti-clockwise direction (shown by an arrow in FIG. 1) respectively. The pawl means 11 can be engaged with one of the teeth by the action of said coil spring 15. The hook 13 is biased by the coil spring 15 so as to be engaged with the pawl means 11, wherein said hook 13 is engaged with the hanger portion 14 when the pawl means 11 moves in relation to the teeth 7 and reaches on the land section 8. On the movable member 5, a projecting wall 16 is provided at the position corresponding to the hook 13. Said projecting wall 16 collides with the hook 13 and acts to release the engagement between the pawl means 11 and hook 13 against the function of the coil spring 15 when said pawl means 11 is engaged with the tooth 7 arranged at left end as shown in FIG. 1. Further, support means 1 and movable member 5 are operatively connected with each other through a coil spring 17. Said coil spring 17 functions so as to rotate the movable member 5 about the pivot shaft 4 in clock-wise direction in FIG. 1.
However, in the case of such conventional headrest, the headrest body 20 rotatably mounted on the suppot stay 2 is inclined forward and backward so as to adjust the front and rear positions thereof. Therefore, a sufficient stroke for moving the headrest forward and backward cannot be obtained, and most of the passengers cannot be satisfied. And, the mechanism for controlling the rotation and return movement of the headrest is somewhat too complicated, thereby making the cost high and its durability doubtful.
Further, in the case of the conventional headrests which are operated by the knob or the like make it necessary to attach or project the knob to or from them. Therefore, their design is limited to some extent and their shape becomes complicated, thereby making their cost high and their safety retarded by the knob projected. On the other hand, the otheres which have no means such as the knob are likely to become complicated in construction, thereby making their cost high, and their durability doubtful.